Naphtha (petroleum), light steam-cracked arom.

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP, QSAR calculation, acceptable with restrictions.

Justification for type of information:

Episuite and the BIOWIN models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Constituents within LOA streams fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

(Q)SAR model reporting (QMRF)

Principles of method if other than guideline:

BIOWIN v4.1 in EPISuite 4.1 (2017). The Biodegradation Probability Program (Biowin) estimates the probability for the rapid aerobic biodegradation of an organic chemical in the presence of mixed populations of environmental microorganisms. As recommended in the ECHA guidance R.7b, BIOWIN 2, 3, 5 and 6 were used to predict the ready biodegradability of constituents of the category:

BIOWIN 2 =  nonlinear probability model
BIOWIN 3  =  expert survey ultimate biodegradation model
BIOWIN 5  =  MITI linear model
BIOWIN 6  =  MITI nonlinear model

Biodegradability estimates are based upon fragment constants that were developed using multiple linear or non-linear regression analyses, depending on the model. BIOWIN 2 is intended to convey a general indication of biodegradability under aerobic conditions, and not for any particular medium (Howard et al., 1992). BIOWIN 3 yield estimates for the time required to achieve complete ultimate and primary biodegradation in a typical or "evaluative" aquatic environment (Boethling et al., 1994). BIOWIN 5 and 6 are predictive models for assessing a compound’s biodegradability in the Japanese MITI (Ministry of International Trade and Industry) ready biodegradation test; i.e. OECD 301C (Tunkel et al., 2000).

The use of QSAR estimates to predict the biodegradability of hydrocarbons are included in the training sets of the BIOWIN. The databases were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Oxygen conditions:

aerobic

Inoculum or test system:

not specified

Details on inoculum:

Not applicable

Based on:

other: QSAR calculation

Parameter followed for biodegradation estimation:

other: QSAR calculation

Details on study design:

Not applicable

Preliminary study:

Not applicable

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 2

Value:

>= 0.37 - <= 1

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

calculated rating of total degradation time (QSAR/QSPR)

Remarks:

BIOWIN 3

Value:

>= 2.33 - <= 3.54

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 5

Value:

>= 0.201 - <= 0.628

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 6

Value:

>= 0.12 - <= 0.88

Remarks on result:

other: Result from QSAR prediction.Range based on the measured constituents in the streams.

Details on results:

BIOWIN 2, 5, and 6 Result Classification: A probability greater than or equal to 0.5 indicates “Biodegrades Fast” and a probability less than 0.5 indicates “Does NOT Biodegrade Fast”
BIOWIN 3 Result Classification (primary and ultimate): 5.00 - hours, 4.00 - days, 3.00 - weeks, 2.00 - months, 1.00 - longer. A probability greater than or equal to 2.75 indicates "Biodegrades Fast".
Details of the constituents and how their BIOWIN half-lives relate to their persistence assessment are found in the PBT report attached to Section 13 (see cross-reference), and also in the document attached as background material.

Results with reference substance:

Not applicable

 

Model	Biodegrades fast (No. of consituents)	Does not biodegrade fast  (No. of consituents)
BIOWIN 2	218	22
BIOWIN 3	204	36
BIOWIN 5	88	152
BIOWIN 6	156	64

Validity criteria fulfilled:

not applicable

Conclusions:

The BIOWIN models predict a high probability of ready biodegradability for a number of measured constituents of these streams. Out of the 240 constituents of the category, and according to the criteria in the R.7b Information Requirement Guidance from ECHA, the following is concluded:
- BIOWIN 2 predicted 218 constituents biodegrade fast
- BIOWIN 3 predicted 204 constituents biodegrade fast (within weeks)
- BIOWIN 5 predicted 88 constituents biodegrade fast
- BIOWIN 6 predicted 156 constituents biodegrade fast
Details of the constituents and how their BIOWIN half-lives relate to their persistence assessment are found in the PBT report attached to Section 13 (see cross-reference), and also in the document attached as background material.

Executive summary:

The ready biodegradability of measured constituents (at equal or above 0.1% w/w) of this category have been predicted using the EPISUITE v4.11 BIOWIN models (2017), which use methodology described by Howard et al. (1992), Boethling et al. (1994) and Tunkel et al. (2000). Of the 240 constituents, and according to the criteria set out in the ECHA R.7b Information Requirements Guidance, 218 (BIOWIN 2), 204 (BIOWIN 3), 88 (BIOWIN 5) and 156 (BIOWIN 6) were predicted to be readily biodegradable based on the different models, with 218 constituents having at least one prediction of a high probability that it will biodegrade fast.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 September 2003 - 22 October 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as unpublished report, acceptable without restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

Clarifications provided

GLP compliance:

yes

Oxygen conditions:

not specified

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

from Clinton Sanitary Wastewater Treatment Plant Annadale NJ USA

Duration of test (contact time):

28 d

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Triplicate test systems used to evaluate biodegradability of the test and positive control substances at mean concentrations of 52.67 mg/L and 51.19 mg/L respectively. Blank test systems, which did not contain the test or positive control substance were run concurrently in triplicate. The total suspended solids (TSS) of the activated sludge was determined to be 3.32 g/L. The inoculum was added at a 1% loading volume of sludge supernatant to test medium. The microbial count of the inoculum was 105 CFU/mL. One litre of test medium, which was aerated for 24 hrs with carbon dioxide free air, was added to each one litre respirometer flask. The test substance was weighed in an airtight syringe and injected into the test medium. The test system was sealed immediately after addition of the test substance. An aliquot of the positive control stock solution was added to the appropriate test flasks. An unacclimated activated sludge inoculum was used in this study. Temperature range of 22 + 1 degrees C.

Reference substance:

other: Sodim benzoate 99%

Preliminary study:

Not reported

Test performance:

Not readily biodegradable

Parameter:

% degradation (O2 consumption)

Value:

7.3

Sampling time:

28 d

Results with reference substance:

88.93% after 28 days

Validity criteria fulfilled:

yes

Interpretation of results:

other: Not readily biodegradable

Conclusions:

Pyrolysis C10 + Fuel Oil (from Pyrolysis Gasoline Distillation) achieved a mean percent biodegradation of 7.3% and cannot be considered readily biodegradable

Executive summary:

This is a GLP compliant, guideline study which is considered adequate for assessment. Pyrolysis C10 + Fuel Oil (from Pyrolysis Gasoline Distillation) achieved a mean percent biodegradation of 7.3% and cannot be considered readily biodegradable

Description of key information

Biodegradation data are available for 1 streams within this category (ExxonMobil (2004)).The data are considered reliable and suitable for assessment. Data showed the test substances to be not readily biodegradable. Biodegradation rate was 7.3 % in 28 days. However, of the 240 measured constituents (at equal or above 0.1% w/w), and according to the criteria set out in the ECHA R.7b Information Requirements Guidance, 218 (BIOWIN 2), 204 (BIOWIN 3), 88 (BIOWIN 5) and 156 (BIOWIN 6) were predicted to be readily biodegradable based on the different models, with 218 constituents having at least one prediction of a high probability that it will biodegrade fast.

 

The category is considered inherently biodegradable based on ready biodegradability tests and QSAR data. Data will be read across to other category members.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

In an OECD 301F ready biodegradation study 1 stream from this category (CAS No: 68921 -67-5) was shown to degrade by 7.3% in 28 days and is therefore not considered readily biodegradable.

 

The ready biodegradability of measured constituents (at equal or above 0.1% w/w) of this category have been predicted using the EPISUITE v4.11 BIOWIN models (2017), which use methodology described by Howard et al. (1992), Boethling et al. (1994) and Tunkel et al. (2000). Of the 240 constituents, and according to the criteria set out in the ECHA R.7b Information Requirements Guidance, 218 (BIOWIN 2), 204 (BIOWIN 3), 88 (BIOWIN 5) and 156 (BIOWIN 6) were predicted to be readily biodegradable based on the different models, with 218 constituents having at least one prediction of a high probability that it will biodegrade fast.